Phonograph horn for portable phonographs



April 1, 1941. R. H. CQFFREN 2236.520

rnonoemrn norm FOR PORTABLE PHONOGRAPHS Filed April 23, 1940Sheets-Sheet 2 mizllnrd Hal Coffren.

April 1, 1941. R COFFREN 2,236,520 I PHONOGRAPH HORN FOR PORTABLEPHONOGRAPHS Filed April 25, 1940 3 SheetsSheet 5 9 awenhrb Ridulnl Hal(offre n Patented Apr. 1, 1941 PHONOGRAPH HORN FOR PORTABLE PHONOGRAPHSRichard Hal Coflren, Washington, D. 0.

Application April 23, 1940, Serial No. 831,248

8 Claims.

The object of my invention is to provide a novel horn for portable andother phonographs which better reproduces the tones of records thanhorns heretofore devised, which is very compact and is especiallyadapted for use on."

portable phonographs which have cabinets of relatively small size andshallow depth.

It is an especial object of my invention to provide a horn which willmodify the vibrations of bass notes so that a more accurate andbeautifulreproduction of the original recording may be obtained than hasbeen possible with horns of other types.

It is also an object of my invention to have the tone arm concealed bybeing disposed under the? platform of the phonograph and to provide aconstruction that will so modify the bass notes reproduced as to preventblasting and undesirable vibrations; and to provide a tone modifier orvisible horn on the motor board of such shape that it will take uprelatively little vertical room and will partly overlie the turntablewhereby to make it possible to produce a compact portable phonograph ina compact and relatively small cabinet, and which will reproduce toneswith unusual clearness.

I attain these and other objects of my invention by the mechanismillustrated in the accompanying drawings, in which- Figure l is aperspective view of the inven-=:

tion installed in a portable phonograph;

Fig. 2 is a horizontal section on line 2-2 of i Fig. 3 is a verticalsection on line 2-2 of Fig. 1;

Fig. 4 is a vertical section of a modification of the invention on aline similar to section line 3-3 of Fig. 2;

Fig. 5 is a view partly in horizontal section and partly in bottom planof a modification of the.

' du'cer 1 and reproducer arm 8. The cover is supported in the slantingposition shown in Fig. l by a bracket 2a. and pivotally mounted slottedmetal arm 2b. The cabinet may be fastened by any suitable fasteningmeans for transportawaves against the left hand wall I la.

tion. All of these elements are conventional ex cept that in applicantscabinet, the cover 2 is ot ljrelatively greater depth than is usual inportable phonograph cabinet covers.

iiMounted on the phonograph platform or motor board I is a tone modifieror visible horn comprising like forwardly expanding or slanting hornwalls Ha; supporting a flat horn top I l, upwardly curved rear walls Ilb continuing in a flat top wall l'i 'r'extending parallel with themotor board and ei rt ending only part way over the turntable so as notto interiere'with the necessary swing range ot-imovement of. thereproducer arm.

T-he reproducer arm 8 is in communication with a concealed wooden tonearm or horn 9 substantially square in cross section and disposed beneathand concealed by the motor board aportion of the motor forming the upperwall of said tone arm, as shown in Figs. 3 and 4. Tone arm 9 extendsparallel with the adjacent side of the cabinet and curves at the rearand terminates in a rear tone arm section 9a disposed parallel to therear wall of the cabinet and at right angles to the tone arm 9. The tonearm sections 9 and 9a. gradually expand in crosssectional area from thereproducer horn to their mouth. Rear section of the tone arm has anupwardly curved end portion 9?) and an oppositely positioned upwardlyinclined wall II] which terminates in the opening Illa of reduced size,as

shown in Fig. 3 adjacent one of the side walls Ha of the outer horn II.By this construction of the tone chamber amaterial improvement in thequality of tone reproduction is obtained. Inclined wall I0 reduces the.area of the outlet Illa of the horn and controls the bass notes,

' tending to increase their volume without any tremendous increase inforce. The slanting disposition of wall 10 operates to reflect the toneThe opening lfl'a; which is reduced in cross sectional area as comparedwith the cross sectional area of the horn modifies the tone and reducesthe surface noise of therecord caused by friction of the needle'in thesound track of the record, thereby operating to greatly improve thequality of the reproduction of the recorded tones.

As show in Figs. 5 and 6, I may provide a modified form of my inventionwith the reproducer arnr disposed in the same relative position in thecabinet as shown in Fig. 1 but with the horn 90 extending from thereproducer arm parallel with the front wall of the cabinet and thencethe portion 9 of the tone extending along the left hand side wall of thecabinet, and thence the portion of the tone arm extending to itstermination adjacent the central portion of the rear wall of thecabinet, with the inclined wall H3 in reversed position from that shownin Fig. 1, or in other words, in a reversed disposition of the born fromthat shown in Fig. 1 and with a consequently longer tone arm due to thearrangement as described. An advantage that is obtainable by suchconstruction is that as a result of the provision of such a longer tonearm, increased volume of tone would be reproduced. In this form. of theinvention as well as in the forms shown in Figs. 1 to 3, the end Illb ofthe of the curved end portion 9b of the horn,'thus providing arestricted opening 19a which is only about one-half the cross sectionalarea of the stricted opening and disposition of inclined wall it! is toreduce the blasting effect of bass notes and to produce a better tonequality without any noticeable reduction in the volume of the tone.

What I claim is:

1. In combination with a portable phonograph having a turntable,reproducer, reproducerqarm, motor board and portable cabinet, a tonearmin communication with the reproducer arm andpositioned beneath andconcealed-by the motor board, said motor board forming thetop wall ofthe tone arm, said tone arm extending parallel with the side of thephonograph adjacent to which the reproducer arm is mounted and curvingnear the rear of the cabinet and'thence extending parallel with the rearof the cabinet and gradually expanding in cross-sectional area butterminating in an opening of reduced size at the surface of the motorboard, a slightly upwardly inclined wall extending from the surface ofthe motor board and reducing the cross-sectional area of the opening ofthehorn from beneath the motor board to modify the tone of bass notes, atone-modifying horn positioned over the aforesaid opening and above themotor board and supported thereon and comprising an upwardly andforwardly curved rear wall continuing forwardly as a horizontal topvwall and disposed parallel with the motor board and extending only partway over the turntable to prevent interference with the reproducer arm,and outwardly expanding side walls on which said topwall is supportedand which in turn are mounted on the motor board, the motor boardforming the bottom wall of sai-dhorn.

2. In combination with a portable. phonograph having a turntable, areproducer, a,,reproducer arm, a motor board, and a portable cabinet, atone arm positioned directly beneath and'concealed by the motor boardand in communication at one end with the reproducer arm and terminatingin an opening at the surface of the motor board at the rear portionthereof, an upwardly inclined wall extending from the surface of themotor board to reduce the cross-sectional area of the aforesaid openingand to reflect and modify the tone, a horn positioned over said openingand above the motor board and supported thereon, said horn comprising anupwardly a forwardly curved rear wall continuingforwardly as ahorizontal top wall disposed parallel with the motor board but extendingonl part wayvovelr. turntable to prevent interference with thereproducer arm, an outwardly extending side, wall .on which said topwall is supported, themotorboard forming the bottom wall of said horns;

3. In combination with a portable phonograph having a turntable, areproducer, a reproducer arm, a motor board, and a portable cabinet, ahorn positioned beneath and concealed by the motor board and having theunderside of the motor board as its top wall, said horn having aninclined wall extending slightly upward above the surface of the motorboard and reducing the size of the opening of the horn and reflectingthe tone waves, a horn mounted over said opening and above the motorboard and supported thereby and comprising an upwardly and forwardlycurved rear wall continuing forwardly as a horizontal top wall andextending only part way over inclined wall lfl is relatively close tothe endl'll'c f I the turntable, outwardly e p d s de wa s n which saidtop wall rests, the side walls resting on the motor board, and the motorboard forming the bottom wall of said visible horn.

4. In combination with a portable phonograph haying a turntable,reproducer, reproducer arm,

' a motor board, and a phonograph cabinet, a tone arm in communicationwith the reproducer arm and disposed beneath the motor board andextending parallel with one side of the phonograph cabinet and curvingat the rear and. thence extending parallel with the rear of the cabinet,the motor board forming the top wall of the said tone arm, said tone armgradually expanding in crosssectional area and extending a shortdistance above the surface of the phonograph motor board and terminatingin an opening of reduced crosssectional area, an upwardly and forwardlycurved wall extending over the open end of the aforesaid tone arm andcontinuing forward horizontally and extending part way over theturntable, ex panding side walls on which said top wall is secured, saidside walls being mounted on the motor board and the motor board formingthe bottom wall of the portion of the horn visible above the motorboard, whereby to increase the volume of tone and improve the tonequality.

5. In combination with a phonograph of the type described, having aturntable, a reproducer, a reproducer arm, a motor board, and a portablecabinet, a tone arm having one end in communication with the reproducerarm and positioned beneath the motor board and extending around thefront, thence adjacent one side wall and thence adjacent a portion ofthe rear wall to approximately a middle plane of the cabinet, said tonearm expanding in cross-sectional area, an upwardly inclined wallextending from the surface of the motor board part way over the openingof said horn to reduce its cross-sectional area and to reflect the tonewaves, and a horn positioned over said opening and on the motor board,said horn comprising a forwardly and upwardly curved wall continuing ina horizontal top wall, expanding side walls to which said top wall issecured, the side walls being mounted on the motor board, and the motorboard forming the bottom wall of the said visible born,

6. In combination with a portable phonograph having a turntable, areproducer, a reproducer arm mounted at one front corner of theinstrument, a motor board, a portable cabinet, a tone arm positioned andconcealed beneath the motor board and in communication with thereproducer arm, said tone arm extending parallel to the front wall ofthe phonograph cabinet, thence curving and extending adjacent a sidewall of the cabinet and thence curving and extending one-half way acrossthe rear of the cabinet adjacent the rear wall, an upwardly slantingwall extending from. the surface of the motor board part way across themouth of the concealed tone arm and functioning to reduce thecross-sectional area of the mouth of said tone arm and to modify thetone waves, a visible horn mounted above the surface of the motor boardand over the mouth of the tone arm and comprising opposite likeexpanding side walls extending only part way past the turntable, a topwall mounted on the side walls, and having a rear curved portionextending over the opening of the tone arm which functions to improvethe tone quality and increase its volume without interfering with thereproducer arm, the motor board forming the bottom wall of said visiblehorn.

7. In combination with a phonograph of the type described having aturntable, a reproducer, a reproducer arm, a motor board, and a portablecabinet and hinged cover, a tone arm of expanding size with its smallend in communication with the reproducer arm and positioned beneath themotor board and having the other end terminating in an opening ofreduced size at the surface of the motor board, the motor board formingthe top wall of said tone arm, an upwardly inclined wall extending fromthe surface of the motor board part way over the mouth of the tone arm,

said opening being of reduced cross-sectional area relative to thecross-sectional area of the adjacent portion of the tone arm to reducethe reproduction of surface noises due to friction of the needle on therecord, and an exteriorly positioned horn positioned above the motorboard and over said tone arm mouth, said horn comprising expanding sidewalls and a top and rear wall secured to said side walls and positionedslightly below the inner surface of the cover of the phonograph, themotor board forming the bottom wall of said horn, said horn improvingthe tone quality and increasing its volume.

8. In combination with a phonograph, having a conventional turntable,reproducer, and reproducer arm, a motor board, a horn positioneddirectly beneath the phonograph motor board and extending parallel tothe adjacent side of the motor board and curving at the rear and thenceextending parallel with the rear of the cabinet and gradually expandingin cross-sectional area and terminating in a reduced size opening at thesurface of the phonograph motor board, an upwardly inclined wallextending part way over the aforesaid open end of said horn to reflectand modify the tone waves, a horn mounted above the phonograph motorboard and over said opening and comprising an upwardly curved rear wallcontinuing forwardly as a horizontal top wall disposed parallel with themotor board but extending only part way over the turntable so as not tointerfere with the reproducing arm, and outwardly expanding side wallsof uniform width resting on the motor board and on which said top wallis supported.

RICHARD HAL COFFREN.

